Blister packs for drugs in tablet form or in the form of powder or liquid enclosed in a capsule have been known for a long time. The blister pack consists of a flat sheets of foils covering each other and being attached to each other. One, relatively rigid foil, most commonly called the base, comprises cavities or open "blisters", for accommodating a tablet or capsule each, while the other foil is flat and most commonly called the lid, seals the opening of the cavities or blisters. The most commonly used sealing process is heat sealing, at least one of the foils having thermoplastic properties, and at present the manufacture of the pack is most rationally carried out by continuously joining webs of the foils for said sealing, and cutting them to said packs.
Examples of materials for the lid are hard aluminium, soft aluminium, paper, polyester, PVC, and examples of materials for the base are aluminium laminate, polypropylene, PVC/Aclar, PVC/PVDC. Different laminates as basic material for these foils are also known.
A plurality of blister packs are normally placed in an outer package, a box or carton, which constitutes a unit sold by, for instance, pharmacies. A blister pack may contain, for instance, a weekly dose of drugs and comprises seven blisters, each containing a daily dose, and the package may contain a four-week dose, i.e. four flat blister packs.
A problem with such conventional blister packs is that they are bulky and voluminous owing to the construction of the blisters, and therefore the package must be voluminous. The voluminous package involves heavy expenses, e.g. heavy expenses for the handling and transport and heavy stock-keeping expenses. Furthermore, due to its measures, e.g. large sides, the voluminous package will be rather unstable, which will also render the manufacturing and handling of the package difficult.
Another problem with the present package is the ability to reach the blister pack in the the package having engaging flaps and slits. The stability of the package, which is weakened by the lid opening, could cause the user to easily drop the package when taking a blister pack out of the package, whereby the rest of the blister packs in the package falls out.
Attempts have previously been made to reduce the volume requirement of the outer package, by packing the blister packs in pairs in a package, one blister side facing the other blister side. The term blister side refers to the bubble face of the blister pack, i.e. the face on which the blisters protrude. This has made it possible to arrange the lid of the box on one side of the box, one short side. However, by this arrangement a new problem occurs. The blister side of the blister pack being pulled out of the box takes along the blister pack whose blister side faces the blister side of the pack that is being pulled out. Furthermore, the packing of identical blister packs facing each other in pairs will cause the blister packs to be offset with respect to each other. A stack of such blister packs will present free edges, which can easily be damaged during handling or transport.
Besides, in case of an odd number of blisters in a blister pack, the centre of gravity of the blister pack will be offset relative to the centre of symmetry, which may cause problems during the packing phase of the manufacture of the blister packs. There is a great risk that the blister pack will be askew, whereby some of the blisters will be damaged.